Admit it: you don’t know what an alternator does. Or maybe you do, but you haven’t a clue what macros are. Oh, you know cars and you hit your protein goals? Congratulations. It must be nice to have at least a couple parts of life figured out.
For the rest of us, it’s perfectly normal to nod along when people toss around niche jargon, only to pull out our phones later to google “serpentine belt connects what” and “how much hummus is too much hummus?”
Every field has its own language, and solar lighting is no exception. Autonomy. Operating profiles. Effective Projected Area (?!). When we first got into solar, none of us knew what these meant. Now, we use them every day, but we haven’t forgotten what it’s like to hear them for the first time and think, “come again?”
That’s why we made this glossary: a plain-English guide to the weird and wonderful world of solar lighting. Whether you’re planning a project, decoding a spec sheet, or just keen to learn something new, you’ll find what you need right here.
If you’ve been here before, you know we talk about this one a lot. It’s our thing. Our M.O. Our North Star… which is why we’re putting it first. Solar sizing means matching a system’s energy collection (panels!) and storage (batteries!) to the project: namely, solar insolation, temperature, light output, and runtime. Get it right, and your lights stay on. Get it wrong? You’ll find out what dusk-to-not-quite-dawn looks like.
The solar engine is the part of the system we—Sol, hi!—build. It’s also the part that powers the fixture built by our friends at Acuity. It includes the panels, batteries, and charge controller, which regulates how energy is collected, stored, and delivered to the light. We may or may not have coined the term ourselves… just one of the many ways we innovate.
The part of the system that makes the light. It’s the visible piece mounted at the top of the pole—typically on some sort of arm—that produces and directs illumination where it’s needed. You might also hear it called a luminaire in certain circles, but we like to keep things simple: it’s a light fixture.
>> The lighting world has its own lexicon, and we’re not diving too deep into it here (we make solar engines, remember?). But if you want to brush up on lighting-specific terms, here’s a list of 20 important ones—and here’s a whole lot more.
The EMS is the “brains” of the operation, a small electronic board that does a big job. It controls how energy moves from the battery to the fixture, constantly checking how much energy is stored and adjusting power flow to match what’s available. If we’re feeling fancy, we might say it uses “patented, AI-based algorithms to prolong lighting performance,” but really… it’s what keeps the light lit.
An operating profile is the schedule that controls when and how a solar light runs: when it turns on, when it turns off, and what it does in between. A basic dusk-to-dawn profile stays bright all night, while advanced ones dim during low-activity hours or respond to motion. The right profile balances lighting needs with energy use, keeping systems reliable and efficient even in low-solar conditions.
Sometimes called backup power, autonomy is how long a solar light can run without a recharge. It’s what keeps the system operating through cloudy stretches or unexpected weather. We recommend at least two days of autonomy for most locations, especially if your winters are long, gray, or just emotionally damp.
Adaptive lighting adjusts light levels in real time based on what’s happening around it—like traffic, weather, or pedestrian activity. Instead of running at one brightness all night, the system dims when things are quiet and brightens when they pick up. The result: light where and when it’s needed, saving energy and reducing light pollution.
These two get mixed up all the time, even by lighting people. Efficacy measures how well a light source converts electrical power into visible light—lumens per watt. Efficiency, on the other hand, compares how much light a fixture actually emits to how much the light source inside it produces. They’re related, but not interchangeable.
Pro tip: When you’re comparing fixtures, efficacy is usually the metric that matters most.
Here’s one to pull out the next time you want to impress a date: EPA is the total surface area of a lighting system exposed to the wind—fixture, solar engine, and pole included. It’s measured in square feet and helps determine how much wind force a structure will face. A higher EPA means more wind resistance to consider when selecting and engineering poles. Romantic, right?
We’ve covered power and smarts, and now we’ve come to the tenon. Maybe not the flashiest part of the system, but definitely critical. It’s the short metal piece at the top of the pole that connects the solar engine, keeping everything straight, stable, and secure. Small but mighty, it ensures proper alignment and stability for the entire system.
Solar lighting has its own language, but guess what? Now you speak it! Hopefully this glossary makes these terms a little more approachable, and maybe even a little interesting. Of course, we’ve only covered the basics here, so if you spot a term on our site (or anywhere else) that leaves you wondering, just ask. We’re always happy to shed a little light.
(Can’t stop, won’t stop!)
